A "ferocious" fire at a block of flats which caused £15,000 of damage is being treated as suspicious, police have said.
The blaze broke out at about 9pm on Friday in the stairwell of the three-storey building at Chester Square in the Mayfield area of Dalkeith. Lothian and Borders Fire and Rescue Service said it is believed the fire was started deliberately.
Three men and a woman were treated at the scene by ambulance staff but did not require hospital treatment. At the height of the blaze, 15 firefighters attended.
Police said all residents needed to be re-housed and the damage is estimated to be in the region of £15,000.
Jeff Douce, group commander, said: "This was a ferocious fire which reached as far as the first floor of the stairwell.
"The materials burning were giving off a lot of thick, black smoke, meaning the residents needed to be led to safety by firefighters. Crews also pitched a ladder at the back of the building to reassure residents on the higher floors until the blaze was under control."
A spokesman for Lothian and Borders Police said: "This was a deliberate act which could have had serious consequences, and we are appealing for any information that can assist our inquiries. Anyone who was in the area of Chester Square around 9pm on Friday, who noticed anyone acting suspiciously in the area, should contact police immediately."